1. Field of the Invention
The present invention relates to an image pickup apparatus using a solid state image pickup device.
2. Related Background Art
A single plate color camera has, for example, color filters and a single solid state image pickup device to form an image through each color filter. The color filters for transmitting different color lights are sequentially arranged on photosensitive elements on the solid state image pickup device, an object image is formed on the solid state image pickup device, and chrominance signals and a luminance signal which have been space modulated are obtained from the solid state image pickup device.
In such a color camera, there is a color camera which obtains chrominance signals from an image pickup device having a color filter arrangement as shown in FIG. 1 by executing the following processes.
In the image pickup device, a video signal is generated by performing the following scan. In even number fields, the charges of the photosensitive elements of the n-th and (n+1)th horizontal lines which are neighboring in the vertical direction and the charges of the photosensitive elements of the (n+2)th and (n+3)th horizontal lines are respectively added and transferred. In the odd number fields, the charges of the photosensitive elements of the (n+1)th and (n+2)th horizontal lines which are neighboring in the vertical direction and the charges of the photo sensitive elements of the (n+3)th and (n+4)th horizontal lines are respectively added and transferred and outputted. By such scans, signals constructed by the following primary color chrominance signal component ratios are outputted.
n-th line of the even number fields: PA1 (n+2)th line of the even number field: PA1 (n+1)th line of the odd number field: PA1 (n+3)th line of the odd number field:
on the mth column, Mg+Cy=R+G+2B;WB PA2 on the (m+1)th column, G+Ye=R+2G;GR PA2 on the m-th column, G+Cy=2G+B;GB PA2 on the (m+1)th column, Mg+Ye=2R+G+B;WR PA2 on the m-th column, Cy+G=2G+B;GB PA2 on the (m+1)th column, Ye+Mg=2R+G+B;WR PA2 on the m-th column, Cy+Mg=R+G+2B ;WB PA2 on the (m+1)th column, Ye+G=R+2G;GR
A matrix including four predetermined numbers is multiplied to such four kinds of signals WB, WR, GR, and GB, thereby extracting the primary color component of one of three primary colors R, G, and B. Therefore, primary color signals of red (R), green (G), and blue (B) are obtained by, for example, executing arithmetic operating processes based on the following numerical expression (1). ##EQU1##
That is, R is obtained by respectively multiplying x.sub.0, x.sub.1, x.sub.2, and x.sub.3 to the four kinds of signals WB, WR, GR, and GB. G is obtained by respectively multiplying y.sub.0, y.sub.1, y.sub.2, and y.sub.3 to the four kinds of signals WB, WR, GR, and GB. B is obtained by respectively multiplying z.sub.0, z.sub.1, z.sub.2, and z.sub.3 to the four kinds of signals WB, WR, GR, and GB.
Since the above four kinds of signals are output by the above scanning method in a time-division manner, they are not simultaneously derived. Therefore, it is constructed so that the same kind of signals can be always derived by delay elements of one horizontal line and one pixel and a selecting circuit.
In the single plate image pickup device, however, a luminance signal component is also separated from the four kinds of chrominance signal components obtained from the image pickup device. Actual color transmitting characteristics of color filters Mg, Ye, Cy, and G in FIG. 1 exhibit RGB transmitting characteristics which are different from those mentioned above. There is a drawback such that the RGB signals obtained by performing color separating processes or demodulating processes don't show good color separating characteristics.
On the other hand, since the RGB primary color components are directly obtained from the output of the image pickup device, there is a drawback such that the hue cannot be easily adjusted as it is demanded.